The present invention relates to control signaling and data transfer in a computer network. More specifically, it relates to a method and apparatus for sending delay sensitive information on a higher cost network connection while sending non-delay sensitive control and status information on a lower cost network connection.
As is known in the art, a variety of computing devices are often connected together to form a computer network. The computer network may be a Local Area Network (xe2x80x9cLANxe2x80x9d) that connects devices over a small geographical area, or a Wide Area Network (xe2x80x9cWANxe2x80x9d) that connects devices over a large geographical area. The connection strategy used to connect devices in a network is called the xe2x80x9cnetwork topology.xe2x80x9d
Devices in a network are typically connected with circuit switched, message switched, and packet switched connections. A circuit switched connection is a dedicated communications circuit between two devices. The communications circuit may be a physical or a virtual circuit connection. A message switched connection establishes a non-dedicated message route when a unit of information is sent. Different units of information may travel over different routes in a message switched connection. A packet switched connection divides original information into multiple packets on the transmitting end, transmits the packets separately, and re-assembles the packets into the original information on the receiving end. The transmission route may be dedicated (e.g., virtual circuit) or non-dedicated (e.g., datagram) in a packet switched connection.
Additional devices are typically required to make connections between dissimilar network topologies. For example, repeaters, bridges, gateways and routers are used to connect networks with different topologies. Repeaters copy individual bits between network topologies. Bridges store and forward data frames between network topologies. Gateways store and forward data packets between dissimilar network topologies. Routers translate differences between network protocols and route data packets to the appropriate device on a network topology.
Computer networks are often created that contain multiple network nodes or network stations. Each node or station may be a network itself and contain multiple computing devices. For example, a WAN can be created with multiple nodes where each node comprises a LAN with multiple computing devices. The nodes in the network are typically connected with one or more connections with dedicated functionalities.
A network connection with a dedicated functionality is often optimal for a selected group of functions, but inefficient for other related functions. For example, delay sensitive connections are optimized for information that is sensitive to delays in transmission, such as voice information, but often inefficient for high bandwidth applications that periodically send large bursts of data. Packet switched networks provide optimized bandwidth utilization for applications that periodically send large bursts of data, but this optimization and the use of error correction techniques (e.g., retransmission) can cause large transmission variations and make such a connection ill suited for information that is delay sensitive.
There are several problems associated with connecting nodes in a computer network with connections with dedicated functionalities. Delay sensitive information is typically sent over dedicated connections that are higher priced connections (e.g., charged time-of-use fees). Delay sensitive information includes voice, real-time video and other information sensitive to transmission delays. Such information can not be sent over connections that may have a large transmission delay without loss of information or loss of quality of information. Non-delay sensitive information and large bursts of data are typically sent over dedicated packet switched connections that are lower priced connections (e.g., charged monthly connection or bandwidth fees).
Control and status information used to control the delay sensitive connections is sent over the higher priced delay sensitive connections along with delay sensitive information. This significantly increases the overall cost of using the delay sensitive connections.
As is known in the art, control and status information can be sent via packet switched networks associated with a delay sensitive network (i.e., a circuit switched network) to decrease the overall cost of using the delay sensitive network. For example, Signaling System Seven (xe2x80x9cSS7xe2x80x9d) known in the telephony arts, sends control and status information for circuit switched connections via a separate packet switched signaling connection. However, use of SS7 requires the computer network use special SS7 packet switching hardware and software on network nodes. This significantly increases the cost of the network. In addition, the SS7 hardware and software is not directly accessible by user applications making SS7 use impractical for most user-to-user network applications.
Delay sensitive networks, such as circuit switched networks typically use Time Division Multiplexing (xe2x80x9cTDMxe2x80x9d), Frequency Division Multiplexing (xe2x80x9cFDMxe2x80x9d) statistical multiplexing, and other multiplexing techniques along with compression to transmit multiple analog or digital channels over a single delay sensitive connection. Sending control and status information over the delay sensitive connection also decreases the number of available channels that can be used to send delay sensitive information. This may cause congestion or delay problems in the delay sensitive connection and further increase the cost of using the higher priced circuit switched network.
Another problem with using dedicated connections is that individual nodes in a computer network may not have information about what delay sensitive connections are available to other nodes in the network and the status of such connections. When a node desires to communicate with another node in the network with a delay sensitive connection, it should be able to effectively make new delay sensitive connection decisions at the lowest possible cost. For example, a first node desires to communicate with a third node via a delay sensitive connection. The first node currently has no direct delay sensitive connection to the third node. However, the first node has a direct delay sensitive connection to a second node, and the second node has a direct delay sensitive connection to the third node. The first node could establish an indirect delay sensitive connection to the third node through the second node if the first node had information about the delay sensitive connections of the second node and the status of such connections (e.g., all delay sensitive channels are busy or there are delay sensitive channels available). A connection from the third node, to the second node, to the first node with an indirect multi-hop delay sensitive connection may be more cost effective than establishing a direct delay sensitive connection between the first and third nodes (e.g., local call instead of a long distance call).
In accordance with an illustrative embodiment of the present invention, some of the problems associated with using dedicated connections to connect nodes in a computer network are overcome. A method and apparatus are described for sending routed delay sensitive information assisted by packet switched networks. The method includes a computer network with multiple network nodes where the network nodes have a packet switched connection to a packet switched network. In an illustrative embodiment of the present invention, the packet switched network is the Internet. However, other packet switched networks can also be used.
Selected network nodes have a delay sensitive connection to a delay sensitive network for sending and receiving delay sensitive information such as voice and real-time video. The delay sensitive connections include multiple delay sensitive connection channels. A selection input is received on a first network node to change the status of a delay sensitive connection between the first network node and a second network node (e.g., requesting a new delay sensitive connection). The status of the delay sensitive connection is changed based on the selection input (e.g., establishing a delay sensitive connection). A control message with a predetermined protocol is sent on the packet switched network to the other network nodes in the computer network indicating the change in status of the delay sensitive connection. The control messages are used by other network nodes to make connection decisions and establish the lowest cost delay sensitive connections. The lowest cost delay sensitive connection may be an indirect, multi-hop delay sensitive connection and may utilize idle delay sensitive channels on a previously established delay sensitive connection between two network nodes. The lowest cost delay sensitive connection may also be a shortest path delay sensitive connection, or a lowest cost delay sensative connection with a desired quality of service.
The foregoing and other features and advantages of an illustrative embodiment of the present invention will be more readily apparent from the following detailed description, which proceeds with references to the accompanying drawings.